Pyrophoric fuel compositions



Oct- 9, 19 M. w. HUNT ETAL PYROPHORIC FUEL COMPOSITIONS Filed Aug. 10, 1959 0 O m m IIO 0 IO WEIGHT PER CENT BORON TRIETHYL IN TRIETHYL AMINE BORANE INVENTOR. RICHARD M. T/LLMAN BY MACK W. HUNT A T TOR/VE Y United States Patent 3,057,763 Patented Oct. 9, 1962 3,057,763 PYROPHORIC FUEL COMPOSITIONS Mack W. Hunt and Richard M. Tillman, Ponca City, Okla., assiguors to Continental Oil Company, Ponca City, Okla., a corporation of Delaware Filed Aug. 10, 1959, Ser. No. 832,728 Claims. (Cl. 14922) This invention relates to pyrophoric fuel compositions and more particularly to such compositions whereby the ignition temperature thereof can be modified as desired.

Pyrophoric fuels for use in air breathing missiles possess a number of advantages over conventional fuels; such as, greater reliability, efficiency, and thrust; however, certain disadvantages are inherent in the specific pyrophoric fuels now available. As for example, the trialkylaluminum compounds and dialkylzinc compounds such as trimethyl and triethylaluminum, diethyl zinc are spontaneously inflammable and furthermore they react violently with water. The boron hydrides are objectionable in that they are very toxic; in addition certain boron compounds are spontaneously inflammable.

The performance index of the various pyrophoric fuels now available can be calculated from the data given below using JP-4 as a standard.

1 JP-4 is a liquid petroleum fraction comprising a mixture of hydrocarbons in the gasoline and kerosene distillation ranges having the physical properties listed below:

50% distillation point 370 F. min. 90% distillation point 2 470 F. min. Reid vapor pressure 2-3 lbs.

2 Performance index:

B.t.u./lb. X Btu/gallon of test fuel B.t.u./lb. X B.t.u./gallon of J P4 An ideal pyrcphoric fuel would be one that has first of all a high performance index. In addition it should be thermally stable, unreactive with water and not be spontaneously inflammable at normal atmospheric temperatures. The latter is important so as to facilitate safe field handling. Obviously none of the fuels listed above possess all the properties desired in an ideal pyrophoric fuel. As for example, triethylaluminum is only slightly better than JP-4 from a performance index standpoint. Triethylboron because of its low specific gravity has a relatively low performance index. Tetraethyl diborane is spontaneously inflammable to a high degree. Triethylamine borane while very stable is not pyrophoric.

It is, therefore, a principal object of the present invention to provide a composition that obviates the disadvantages of the prior art compositions. It is another object of our invention to provide a composition the ignition temperature of which can be varied as desired. It is another object of this invention to provide a composition that is easily handled. Other objects and advantages of the present invention will become apparent from the following description of our invention.

To the accomplishment of the foregoing and related ends, this invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various Ways in which the principle of the invention may be employed.

Broadly stated the foregoing objects and advantages are attained by employing as a pyrophoric fuel composition triethylamine borane having admixed therewith varying amounts of an organo boron compound or a trialkylaluminurn compound.

Before proceeding with specific examples illustrating our invention, it may be well to indicate in general the nature of the materials required in the process.

Suitable organo boron compounds for admixing with the triethylamine borane include triethylboron and tetraethyldiborane. Suitable trialkylaluminum compounds are those which are pyrophoric and include compounds such as trimethylaluminum, triethylaluminum, etc. Triethylaluminum is the preferred trialkylaluminum compound.

As to the amounts of the various components making up the pyrophon'c fuel composition we have found that a suitable range of the triethylamine borane varies from to 95 percent. A preferred range varies from to percent. Suitable and preferred quantities of the second component regardless of which specific compound is used as the second component vary from 25 to 5 percent and 15 to 10 percent respectively. All percentage figures are on a weight basis of the total composition.

The addition of one of the second components to triethylamine borane in accordance to our invention will lower both the ignition temperature and the melting point of the final composition. This is accomplished with very little sacrifice in the performance index of the final composition compared to that of the triethylamine borane. The lowering of the ignition temperature is apparent from the accompanying drawing wherein the ignition tem perature is plotted versus weight percent triethylboron in triethylamine borane. Similar curves were obtained when each of the other components listed above was admixed with the triethy-lamine borane and the ignition temperatures of the resulting admixture determined.

While particular embodiments of the invention have been described it will be understood, of course, that the invention is not limited thereto since many modifications may be made, and it is, therefore, contemplated to cover by the appended claims any such modifications as fall within the true spirit and scope of the invention.

The invention having thus been described, What is claimed and desired to be secured by Letters Patent is:

1. A liquid pyrophoric fuel composition comprising 75 to Weight percent triethylarnine borane having admixed therewith 25 to 5 weight percent of an organo metallic compound selected from the group consisting of pyrophoric trialkylaluminum compounds, the alkyl groups of which are selected from the group consisting of methyl and ethyl, triethylboron, and tetraethyl diborane.

2. A liquid pyrophoric fuel composition comprising 85 to 90 weight percent triethyl-amine borane having admixed therewith 15 to 10 weight percent of an organo metallic compound selected from the group consisting of pyrophoric trialkylaluminum compounds, the alkyl groups of which are selected from the group consisting of methyl and ethyl, triethylboron, and tetraethyl diborane.

3. The composition of claim 1 wherein the organo metallic compound is triethylaluminum.

4. The composition of claim 1 wherein the organo metallic compound is triethylboron.

5. The composition of claim 1 wherein the organo metallic compound is tetraethyl diborane.

References Cited in the file of this patent UNITED STATES PATENTS Brown Nov. 11, 1958 Kimmel Jan. 6, 1959 

1. A LIQUID PYROPHORIC FUEL COMPOSITION COMPRISING 75 TO 95 WEIGHT PERCENT TRIETHYLAMINE BORANE HAVING ADMIXED THEREWITH 25 TO 5 WEIGHT PERCENT OF AN ORGANO METALLIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF PYROPHORIC TRIALKLALUMINUM COMPOUNDS, THE ALKYL GROUPS OF WHICH ARE SELECTED FROM THE GROUP CONSISTING OF METHYL AND ETHYL, TRIETHYLOBORON, AND TETRAETHYL DIBORANE. 